Effect of kappa-semi-refined carrageenan on the gelatinisation and retrogradation of corn starch and wheat flour

Abstract

The effect of kappa-semi-refined carrageenan (SRC) with different concentration (0.1 %, 0.5%, 1.0%, and 1.5%) on the gelatinisation and retrogradation of corn starches with different amylose content (waxy, normal, high amylose) and wheat flours with different protein content (low protein, medium protein, high protein) was determined. The analysis conducted included pasting properties, thermal behaviour,
freeze-thaw stability and syneresis tests. Addition of SRC to corn starches of different amylose content affected the pasting properties of the corn starches differently.
Addition of SRC Significantly increased the pasting temperature of waxy corn starch but decreased the pasting temperature of normal corn starch (p<0.05). However, pasting
temperature of high amylose corn starch was not altered with addition of SRC (p>0.05). Breakdown viscosities of wary and normal corn starch were reduced with SRC addition (p<0.05), suggesting additional heat and shear resistance of these
starches provided in the presence of SRC. For high amylose corn starch, addition of SRC decreased the peak and final viscosity (p<0.05). Only the setback viscosity of high
amylose corn starch was found to decrease with increasing SRC concentration (p<0.05), while the setback viscosities of waxy and normal corn starch were not affected (p>0.05). Pasting temperature of wheat flours were not modified by SRC
addition (p>0.05). However, addition of SRC increased the peak viscosity and reduced the setback viscosity of all wheat flours (p<0.05). Addition of SRC increased the
gelatinisation end temperature and temperature range of waxy and normal corn starch, while Significantly decrease the gelatinisation enthalpy of high amylose corn starch
(p<0.05), indicating reduced water availability for starch gelatinisation in the presence of SRC. Addition of 1.5% and 0.1% SRC significantly increased the retrogradation of
waxy and high amylose corn starch respectively (p<0.05). The gelatinisation properties of wheat flours were not affected by SRC (p>0.05). The effect of SRC on retrogradation of wheat flours measured by Differential Scanning Calorimeter displayed inconsistent results. However, addition of 0.1% SRC promoted the retrogradation of low protein wheat flour (p<0.05). Addition of SRC successfully decreased syneresis in freeze-thaw cycle and refrigeration (4°C) for one week for both corn starches and wheat flours (p<0.05). Overall, the effect of SRC on gelatinisation and retrogradation
of starch was found to be affected by the amylose content of corn starch. Nonetheless, these properties were less affected by the protein content of commercial wheat flour.